make ui flush output. this makes error happen if printing to /dev/full.

before this change, error happened with some pythons, but not others.
now always happens.
fixes issue 155.

mercurial/commands.py

@@ -2860,6 +2860,7 b' def dispatch(args):'
             else:
                 d = lambda: func(u, *args, **cmdoptions)
 
+            try:
             if options['profile']:
                 import hotshot, hotshot.stats
                 prof = hotshot.Profile("hg.prof")
@@ -2868,8 +2869,8 b' def dispatch(args):'
                         return prof.runcall(d)
                     except:
                         try:
-                            u.warn(_('exception raised - generating profile '
-                                     'anyway\n'))
+                                u.warn(_('exception raised - generating '
+                                         'profile anyway\n'))
                         except:
                             pass
                         raise
@@ -2881,6 +2882,8 b' def dispatch(args):'
                     stats.print_stats(40)
             else:
                 return d()
+            finally:
+                u.flush()
         except:
             # enter the debugger when we hit an exception
             if options['debugger']:

mercurial/ui.py

@@ -132,6 +132,12 b' class ui(object):'
         for a in args:
             sys.stderr.write(str(a))
 
+    def flush(self):
+        try:
+            sys.stdout.flush()
+        finally:
+            sys.stderr.flush()
+
     def readline(self):
         return sys.stdin.readline()[:-1]
     def prompt(self, msg, pat, default="y"):